@Karmalakas, Ahh, I just remember a post dating back a few years: How to get the slug url using the LangSwitcher plugin? .
I responded back then because I had created my own Language-Switcher some time before to tackle the slug issue of LangSwitcher and also its generated hreflangs.
My (private) plugin does not require any redirect, but does need to fetch more pages internally to get the correct translated slug of its ancestors.
Failing Forms because of the redirect were not part of the discussion.